The goal of this proposal is to identify novel regulators of the hypothalamic circuitry that regulates energy homeostasis. In doing so, this approach might provide new targets for developing therapeutic interventions for the treatment of obesity and diabetes. Hypothalamic nuclei such as the arcuate nucleus (ARC), the paraventricular nucleus (PVN) and the ventromedial hypothalamic nucleus (VMH) have well-established roles in the control of metabolic homeostasis. The Ingraham lab recently conducted global gene expression profiling studies to identify novel molecular markers for the VMH. The transcription cofactor Vestigial like 2 (Vgll2) tops the list as the most VMH-enriched gene in the neonatal VMH. Vgll2 is a mammalian homolog of the Drosophila gene Vestigial (Vg) required for wing development. Since Vgll2 expression is highly restricted to the proposed "metabolic center" of the VMH (the dorsal-medial VMH), it is hypothesize that Vgll2 might be involved in regulating the development of the dorsal-medial VMH. As such, this proposal will focus on 1) defining the function of Vgll2 in VMH development and energy homeostasis, and 2) identifying the protein partner of Vgll2 in the VMH and their target genes. To define the role of Vgll2 in VMH development and energy homeostasis, the generation of a VMH-specific Vgll2 knockout mouse is proposed in Specific Aim 1. VMH development in this mouse will be assessed using in situ hybridization and immunohistochemistry. To determine if the disruption of Vgll2 expression in the VMH leads to any abnormal metabolic consequences, mice will be challenged with high fat diet. To identify the protein partner of Vgll2 in the VMH, a neonatal hypothalalmic cDNA library will be screened using the yeast two-hybrid system in Specific Aim 2. To complement this unbiased approach, a "candidate" approach will also be carried out by determining the expression levels of relevant candidates (i.e. the TEA domain family members) in the VMH. The colocalization and direct interaction with Vgll2 will also be examined. In addition, to determine the VMH- specific Vgll2 target genes, the VMH-transcriptome microarray will be used to compare gene expression levels between wild type and VMH-specific Vgll2 knockout mice. Together, the experiments proposed herein will define the physiological function and molecular mechanism of action of Vgll2. Relevance - According to the latest statistics, 2 out of 3 American adults are either overweight or obese. This research proposal aims at understanding how the brain controls body weight and appetite. The goal of this proposal is to identify new targets for the development of drugs to combat obesity, which is a major risk for diabetes, cardiovascular diseases, and even certain types of cancer.